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The Computer Corner

COMPUTERS

By Charles Miller

 

Beware of iPhone Batteries

 

All week long, I have been haunted by the visual of that YouTube.com video I made reference to in this column last week. For those who may have missed it, the surveillance video on YouTube at https://youtu.be/C6IDgHhDpoE shows what happened when one shopper decided to test the authenticity of a replacement Apple iPhone battery by biting down on it. The battery exploded in a ball of flame. In the video, it did not appear that anyone was seriously injured, and I suppose his eyebrows will grow back soon enough.

So after wasting far too much time this week thinking about this, I believe I might have figured out why the shopper in the video would bite down on a battery. Gold is a very soft metal, and people used to test for counterfeit coins by biting down on them to see if their teeth could make a mark. Apple charges exorbitantly high prices for replacement iPhone batteries, so maybe the shopper thought it was made of pure gold and was simply testing to see if it was the real thing.

Many different chemical elements can be used to make batteries. Stick a zinc-galvanized nail and a piece of copper into a lemon, and out will trickle a little electricity generated by the interaction of the two metals and the acid in the fruit.

Other batteries used today are a bit more practical.

Carbon-zinc and alkaline-manganese batteries are the most common throwaway batteries. The materials used to make these are inexpensive, and these batteries cannot be recharged. Silver-zinc batteries are also non-rechargeable and are typically used for hearing aids because of longer life. But they are made of more expensive materials.

The most common rechargeable batteries used to be nickel-cadmium (NiCad). Those batteries worked best when completely discharged before charging them up again.

Today, most mobile devices use batteries composed of Nickel Metal Hydride (NiMh) or Lithium-Ion. These more expensive materials must be treated differently. They should never be discharged completely, because doing so damages the battery and unnecessarily shortens its life.

As the fellow in the YouTube video found out when he bit down on an iPhone battery, some of the chemicals inside the battery can be a bit dangerous. There are exotic chemical mixes that can be used to create batteries that are not in common use exactly because their materials are so potentially dangerous.

One the more interesting of these is the sodium-sulfur battery. It can be constructed from inexpensive materials. It has a very high-energy density, high efficiency of charge/discharge, and a long cycle life. This sounds like the perfect battery except that it has to operate at a temperature of 350°C (662° Fahrenheit), and sodium explodes violently when it comes into contact with water. That poor shopper could have burned his tongue and possibly lost his head had he bitten one of those.

Charles Miller is a freelance computer consultant, a frequent visitor to San Miguel since 1981, and now practically a full-time resident. He may be contacted at 044 415 101 8528 or email FAQ8 (at) SMAguru.com

 

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